Basic focusing question

joeteds

joeteds

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Joe
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Hello all
Now Im really sorry if this is a rediculous and easy question but I always feel like Im doing something wrong when taking pics and always think that I should have done something different to make the pic better even if Im happy with it, I really am my own worst enemy so here is my basic questions -
1. when taking a photo of more than 1 person where should you focus to get everyone pin sharp ? Am I right in thinking that as long as you have a high f number everything should be sharp anyway ? e.g today I was taking close up face pics of my girlfriend and her little girl and so there wasnt loads of light available so couldnt have a high f number and so I didnt really know what to mainly focus on.Does that make sense ?
2. When it comes to landscape shots what does everyone focus on ? as theres so much in the frame that your seeing e.g if you have say a jetty that you have in the foreground leading into the middle of the photo and then an ocean beyond the jetty do you focus on any particular part of the jetty or the ocean etc ? Or say a a hilly landscape with rocks in the foreground, would focus on the hills or the rocks ?

Im sorry if this is really silly but I like to know what everyone does to get the best results
Thanks
Joe
 
1. Focus on what you want in focus... if conditions dictate that you can't use a high f-number then you have to work within that.

2. Again, focus on the bit you want in focus and use a highish f-number for a bit more advanced technique you could look up 'hyperfocal distance'

:)
 
Hey Joe,

Focusing is a complex area and learning the appropriate techniques takes a while, that said the very quick feedback you get on your LCD helps you see the results of your test quickly.

For the Mother and child shot, if you want them to both be in sharp focus set them so that their eyes are the same distance from the camera with the little ones body perhaps in front of the mother. The sharp focus point should be the eyes and in this case I'd use a single focusing point and focus on the little girls eyes reframing as necessary. If the mum is a fraction out of focus it's not the end of the world.

In the case of your landscape shots I would expect in both these cases that the shortish focal length and the probable option of a small aperture will enable both zones to be in focus. You need to focus on a point a little beyond the nearest subject but hey, your subject won't run away, check it on the LCD.

If both zones can't be in sharp focus you need to make a decision, normally focusing on the zone with the most interest and detail, or shoot it both ways and then decide.

John
 
you're not alone

i usually don't get the focusing right either

e.g. little boy which i focused as single point, still wasn't great, but it might be camera shake as had no antishake/vr

DSC_3598_2.jpg
 
It's key to understand that cameras focus in planes not points, so if you want multiple things to be in focus, get them in the focus plane.
 
phototuition said:
Hey Joe,

Focusing is a complex area and learning the appropriate techniques takes a while, that said the very quick feedback you get on your LCD helps you see the results of your test quickly.

For the Mother and child shot, if you want them to both be in sharp focus set them so that their eyes are the same distance from the camera with the little ones body perhaps in front of the mother. The sharp focus point should be the eyes and in this case I'd use a single focusing point and focus on the little girls eyes reframing as necessary. If the mum is a fraction out of focus it's not the end of the world.

In the case of your landscape shots I would expect in both these cases that the shortish focal length and the probable option of a small aperture will enable both zones to be in focus. You need to focus on a point a little beyond the nearest subject but hey, your subject won't run away, check it on the LCD.

If both zones can't be in sharp focus you need to make a decision, normally focusing on the zone with the most interest and detail, or shoot it both ways and then decide.

John
Click to expand...

Thanks alot John thats a great explanation and one I'll keep in mind and keep coming back to
Thanks
Joe
 
Don't forget that the closer you are, the less depth of field you have
 
Joe
Far from a redicolous question! I'm having focusing difficulties myself.

Thanks to everyone who posted comments on Joes problem, you've also given me things to think about.

Dave
 
Not silly at all. Understanding focus and depth of field are fundamentals. It is the ability to control these things that distinguishes DSLRs from compacts.

Have look at this website on depth of field www.dofmaster.com There's an excellent DoF calculator on there, plus lots of other stuff. I will just say that depth of field is controlled by two factors - f/number, and magnification (image size). Basically, if you make the image bigger - by moving closer, or fitting a longer lens - magnification is increased and DoF is reduced. And vice versa.

You'll also find hyperfocal distance helpful for landscape. It's on the link.
 
HoppyUK said:
Not silly at all. Understanding focus and depth of field are fundamentals. It is the ability to control these things that distinguishes DSLRs from compacts.

Have look at this website on depth of field www.dofmaster.com There's an excellent DoF calculator on there, plus lots of other stuff. I will just say that depth of field is controlled by two factors - f/number, and magnification (image size). Basically, if you make the image bigger - by moving closer, or fitting a longer lens - magnification is increased and DoF is reduced. And vice versa.

You'll also find hyperfocal distance helpful for landscape. It's on the link.
Click to expand...

Thats great thanks alot Richard I'll give that a good look through now
 
currently i have my D90 with a 35mm f1.8

main subject is my 9 month old boy

i usually try and get his whole body in and if i want a close up crop afterwards

however i'm finding focus isn't sharp (maybe cos he moves, but even times when he doesn't it is great)

with a 9 month old motoring on all fours, i find it easiest to put in P mode and then move the single focus point to his eyes, but i find it's not pin sharp. would it be i need a higher F setting?
 
P1TSE - sounds to me like you have the focus mode selector on S (the switch on the left side of the lens mount, front of body) It has 3 positions:
M = manual focus
S = single focus, so that you focus and it holds that focus whilst the shutter button is depressed. If your subject moves whislt in this mode the focus does not move with it.
C = continuous focus. On this setting the focus is continuously moving, depending on what you first selected as your focus point. If you try switiching to C, the camera should follow focus on the point you first picked up. How well it does this depends on the other focus settings you have dialled in from the menus.

Go and read the focus section of the manual, thoroughly, to understand how the mechanics of the focus work. Then you can set your camera up to be far more accurate for the task in hand.

For studio type work, where you are doing still lifes. The S will work well, because nothing is moving. For portraits, the S might still be OK, if people are sat, posed. For moving subjects, the C mode is much better. Even your toddler is movig a few inches as you fire the shutter - just enough to move the eys out of the critical focus plane, but not sufficient to lose total focus. Hence your "nearly, but not quite" results.
 
p1tse said:
would it be i need a higher F setting?
Click to expand...

Yes. I don't dare use anything below f/2.8 on a moving subject - at f/1.8, a movement of even just a centimetre will be enough to duff up the focus.

You could try using AI servo - I did this for the following picture where the flower to the bottom right of the centre kept blowing about, and because I was at f/2, I kept losing focus.

IMG_8998_sb.jpg


AI servo with a focus point on the flower tracked it perfectly and ended up with a pin sharp shot. If a consumer level camera can do that on a flower blowing all over the place then I am sure a D90 can do it on a moving child ;) - but I still say up your F stop a little bit.
 
Good question Joe.

Another thing I struggle with is the single point focus or all 9 points (canon).

Doing a bit of reading, I have been using single point focus on portrait type shots (although like Joe, with more than one person its not always clear where that single point should be aimed) on oneshot...

and for moving pics I use AF servo and the 9 point AF.

Not sure if this is a general rule of thumb as I am still exploring it.
 
Lensflare said:
P1TSE - sounds to me like you have the focus mode selector on S (the switch on the left side of the lens mount, front of body) It has 3 positions:
M = manual focus
S = single focus, so that you focus and it holds that focus whilst the shutter button is depressed. If your subject moves whislt in this mode the focus does not move with it.
C = continuous focus. On this setting the focus is continuously moving, depending on what you first selected as your focus point. If you try switiching to C, the camera should follow focus on the point you first picked up. How well it does this depends on the other focus settings you have dialled in from the menus.

Go and read the focus section of the manual, thoroughly, to understand how the mechanics of the focus work. Then you can set your camera up to be far more accurate for the task in hand.

For studio type work, where you are doing still lifes. The S will work well, because nothing is moving. For portraits, the S might still be OK, if people are sat, posed. For moving subjects, the C mode is much better. Even your toddler is movig a few inches as you fire the shutter - just enough to move the eys out of the critical focus plane, but not sufficient to lose total focus. Hence your "nearly, but not quite" results.
Click to expand...


thanks

i'll pick up the manual and have a look tonight
however i'm not sure if i have what you are saying on the D90?
 
trencheel303 said:
Yes. I don't dare use anything below f/2.8 on a moving subject - at f/1.8, a movement of even just a centimetre will be enough to duff up the focus.

You could try using AI servo - I did this for the following picture where the flower to the bottom right of the centre kept blowing about, and because I was at f/2, I kept losing focus.

IMG_8998_sb.jpg


AI servo with a focus point on the flower tracked it perfectly and ended up with a pin sharp shot. If a consumer level camera can do that on a flower blowing all over the place then I am sure a D90 can do it on a moving child ;) - but I still say up your F stop a little bit.
Click to expand...


thanks

i can't view photobucket at work so will look later

will maybe shoot in A mode rather than P. as sometimes with P mode with the f.18 35mm it can stop down that low or f2.8, so may upp it to say f4 and see, although i won't get the DOF i would like. but better to get the subject matter focussed LOL
 
p1tse said:
thanks

i'll pick up the manual and have a look tonight
however i'm not sure if i have what you are saying on the D90?
Click to expand...

You do have af-s, af-c & af-a but yours is on the top right of the D90 - The AF button (with a green dot)..

Press that & turn either the front or rear dial to the acquired setting (this will show up on the Top LCD panel)

The switch that Simon is on about can be found on the D300/300s & upwards (on your D90 it would be where the AF/M switch is on the front)

Hope that helped...
 
​


The AF Mode has three settings. To select these, hold the AF Mode Selector and spin the dial just behind it. You'll see the indication change on the top LCD, and see it change on the rear LCD if you first hit the rear INFO button.

AF-S (AF-Single)

In AF-S, the D90 focuses once, and locks until you let go of the shutter and press it again.

AF-C (AF-Continuous)

In AF-C, the D90 constantly tracks focus as your subject moves in and out.

AF-A (AF-Automatic)

AF-A is the default setting. It's my favorite because the D90 is so smart that it figures out if your subject is moving or still, and automatically selects the correct mode above for each shot!
 
trig's thanks

that is one thing i've not played with. i'm 99.9% certain mine is on af-a (auto)

maybe i should try af-c ago and see what difference it makes, as suggested by lensflare.

although i do find the d90 auto on settings quite clever on most things.

i think the d90 has 11 focus points (top of my head) or 9?

am i ok to look through the viewfinder, see the focus points and move to a single point with the rear D cursor (not sure on name) to focus on eyes?

also I'll put into Aperature mode at f4 and see.
 
No worries just thought that the picture would help out with the reading...

:woot: my 1000th post...
 
P1TSE - I think it should have been directed at Joeteds...original poster. I lost track of who said what!

SORRY FOLKS!
 
tHANKS FOR THE CLARIFICATION tRIGS - YOU'RE RIGHT. i AM USED TO A d3 AND FORGET THAT THE OTHERS AREN'T THE SAME...oh now look, damn caps button!
 
no thanks to all

makes pointing out some basic functions i really should know on the camera
 
Lensflare said:
P1TSE - I think it should have been directed at Joeteds...original poster. I lost track of who said what!

SORRY FOLKS!
Click to expand...

Simon your not the only one, I loose track as well esp when there's few posts made by different members :lol:


Lensflare said:
tHANKS FOR THE CLARIFICATION tRIGS - YOU'RE RIGHT. i AM USED TO A d3 AND FORGET THAT THE OTHERS AREN'T THE SAME...oh now look, damn caps button!
Click to expand...

No worries Simon.... :thumbs:
 
thanks.

i think i can hear some motor more when set on AP-C
i set it onto A f4 while the little one was eating will try and get a pic up to show
 
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